TreeSet Details part 1 [Collection Framework]

[@amileyjones9082]

Well explained! Durga is a great teacher . As this video is 4 years old , i would like to mention here that till java 1.6 null was allowed in TreeSet but it was considered as bug and in java 7 null is not allowed now in TreeSet. From the documentation of TreeSet: NullPointerException - if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements

[@chandrasekharvalisetty1602]

Correct

[@devendrasingraul8905]

Yes

[@amitbm7497]

Thank you for sharing this.

[@ajinkyakottawar9502]

Don't have words to say thank you for Durga sir...😊 They teach us from very basic concepts and in very easy words with live examples, this way it help me to remember in easy way... Keep going sir...😊 Lot's of love to you and your family... ❤️ God bless you Sir... 🙏😇🙏

[@RAHULKUMAR-ye7cj]

Durga sir is a very good teacher. In my whole life, i never meet with such type of sir who taught very well. Lots of confusion in java, but now my all dout is cleared. Thanku so much sir. Is there any video for android except sandeep sir. Please help me.

[@jajatisahoo3831]

For an empty tree-set, when trying to insert null as the first value, one will get NPE from JDK 7. From JDK 7 onwards, null is not at all accepted by TreeSet. However, up to JDK 6, null was accepted as the first value, but any insertion of more null values in the TreeSet resulted in NullPointerException. Hence, it was considered a bug and thus removed in JDK 7.

[@ravikumarsunkhesvarapu9122]

the way u teach is awesome

[@atiqulny]

Very lively, engaging instructor, best in KZbin.

[@jeetendrabarnwal]

Thanks for these awesome videos... just wanted to add one point - null was allowed in Java 6 ..in Java 7 null is not allowed..

[@saradasai7669]

Thank you Sir. Your explanation is very good ,clear and easily understandable.

[@DurgaSoftwareSolutions]

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[@nisargmunjpara5431]

Hello sir these are incredible stuff we are having. Thank you for it. I have question regarding constructors of "TreeSet(Collection c)." In treeset heterogenous objects are not allowed and what if we create/convert ArrayList collection "c"(or any collection object which consists heterogenous objects) into a TreeSet object with " new TreeSet(Collection c) " constructor???? Hows it possible? Thank you..!!!!

[@jasonarora8911]

+Nisarg Munjpara There is no way if there are heterogenous elements.You will get exception.You have to remove heterogenous elements and then you can take advantage of TreeSet(Having duplicate removed + Sorting elements) but no order preserved

[@Skripturz]

Thanks, I was wondering the same thing

[@varunsen2802]

I think in Priority Queue also, heterogenous objects are not allowed, beacuse in PQ elements are inserted in a some sorted order.

[@DurgaSoftwareSolutions]

Hello Varun. Plz contact our online team [e-mail] or call us on this number [phone], 7207212427/28

[@rahulkad5392]

Good job sir 🥰

[@techgyan6233]

Might be some changes in new java version that's why Null not support import java.util.TreeSet; public class InterfacePractice { public static void main(String[] args) { TreeSet treeSet = new TreeSet(); treeSet.add(null); System.out.println(treeSet); } } Exception in thread "main" java.lang.NullPointerException: Cannot invoke "java.lang.Comparable.compareTo(Object)" because "k1" is null

[@DurgaSoftwareSolutions]

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[@santoshaakubathini5937]

Nicely explained.. Awesome..

[@dhrub6]

Hi Sir, I am your student. I got a job after clearing my doubts in Collections and Threads. Thanks a lot. I have a Question. How will we break TreeSet property (it should store Objects in non sorted order)?

[@rexsam3134]

Nice one. You missed mentioning which Java version was used to run the code

[@DurgaSoftwareSolutions]

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[@surendramishra4813]

One thing I am not able to understand please correct me if I am wrong, when 4. TreeSet t = new TreeSet(Collection c); is there then why we need 3. TreeSet t = new TreeSet(SortedSet s); even though SortedSet also a Collection

[@sangeethagopi4362]

I too have the same doubt... someone please clear our doubt

[@senthil7818]

Durga sir plz upload videos on map collections

[@javadsa367]

Before Java 7, it was possible to add null elements to an empty TreeSet.

[@Rohith-ov7vr]

in priorityque also the hetogeneous data not allowed

[@horriblecoder7280]

If you look at the internal implementation of the TreeSet, it uses natural ordering, that means TreeSet uses Comparable interface by default to sort its value by comparing other value. Just think programmatically, how will you compare the null value to other. Is it make sense to compare the value with other(NULL) which doesn't have any value in it. That's why java developer made it TreeSet such a way that, it will throw NullPointerExeption when you try to store null value.

[@horriblecoder7280]

null as first element was considered as bug in java 1.6

[@jvsnyc]

I believe that nulls are the second worst problem in all of computer science and programming. Inconsistent handling of them, i.e. are two nulls equal or not, etc. is the first.

[@rohitlovesnature]

sir, can you please provide videos on hashmap and map interface

[@Modern_revolution]

Thank you so much for your help!

[@manassahoo2750]

Sit please imporve your graphics and light .

[@algorithmsguide5076]

Thankyou sir ji !!

[@devendrasingraul8905]

TreeSet t = new TreeSet(); // null is not allow for empty TreeSet t.add(null); for Empty TreeSet null is not allow . I am using java 1.8

[@kamalapuramsivasankar7]

Thanks sir...

[@I_am_J300]

sir i tried to add thiss......t.add(null) for empty set obj still getting exception.. Exception in thread "main" java.lang.NullPointerException: Cannot invoke "java.lang.Comparable.compareTo(Object)" because "k1" is null

[@DurgaSoftwareSolutions]

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[@ashishshrivastava4532]

Null is not allowed in TreeSet But allowed in Hash Set So I request you to correct this one.

[@MayurKalambkar]

in java 1.8 null value is not allowed in TreeSet. So you are showing program of which version.

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[@sohrabalam9650]

But in my JDK-8, I am adding null in empty TreeSet and getting NullPointerException. E.g. import java.util.TreeSet; public class TreeSetDemo { public static void main(String[] args) { TreeSet treeSet = new TreeSet(); treeSet.add(null); } } Result : Exception in thread "main" java.lang.NullPointerException

[@DurgaSoftwareSolutions]

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[@addicted2headway]

sir, i am trying to insert null value in empty treeset then also i am getting nullpointer exception

[@DurgaSoftwareSolutions]

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[@VarunKumar-yy5sr]

As per explaination, heterogeneous objects are not allowed but also u said default sorting order for numbers is assessing and characters is alphabetical order. If it is the case y can't we insert heterogeneous elements like alphabets as some elements and numbers as some other elements. Because as per explaination numbers should sort in assending order and characters in alphabetical order. Please clarify.

[@ajinzrathod]

If null value is not working even for first time. It was allowed till 1.6. Since 1.7, null value is not allowed even for first time.

[@DurgaSoftwareSolutions]

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[@pranavdeshpande9675]

sir pls upload videos for Queue nad Map too...

[@pal0106]

what happens if we try to create a tree set with the third constructor using a collection of heterogeneous elements?

[@surajmahtosbg]

watch full video

[@WonderfulSound8]

I'm adding null as my first element, but I'm getting NPE))) Here's my code)) TreeSet treeSet = new TreeSet(); treeSet.add(null); System.out.println(treeSet);

[@jvsnyc]

Read Amiley Jones comment!

[@senthil7818]

This collections videos is enough for collection interview question.?Expecting a reply.Thanks in advance

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[@lipikabarman1012]

after 1.6 version it not working sir. We are not able to insert null value in TreeSet

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[@Tarun1kumar1989]

Hi Sir, I have added only null value then also i am getting null pointer exception. import java.util.*; class TreeSetDemo1 { public static void main(String[] args) { TreeSet t=new TreeSet(); t.add(null); System.out.println(t); } }

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[@rickyb8989]

Same with me...getting NullPointerException...guess either Durga is wrong or it was previously allow in earlier jdk version(I am using jdk 1.8)

[@CorporateKahani]

+ricky b hi ricky, it was possible until 1.6 version only

[@aditya12all]

It says in the compatibility notes from Java 6 to Java 7 that the possibility of adding null to a TreeMap was a bug: oracle.com/technetwork/java/javase/…. See also: bugs.sun.com/bugdatabase/view_bug.do?bug_id=5045147

[@parameshyannam8542]

Sir, why TreeSet and TreeMap Are not allowed Heterogenious Objects ??

[@anirbanmajumdar781]

Because the underline data structure is Balanced Tree and it implements Set, so you cannot actually have sorting done on Hetrogenous objects.

[@RAHULKUMAR-ye7cj]

How I know about unicode of a is 97 and unicode value of A is 65. I am confused here.

[@iam_hindhu]

sir , i trying this program ( am using java 1.7) i have an doubt on Null Acceptance .... TreeSet treeSet=new TreeSet(); treeSet.add(null); System.out.println(" tree Set is : "+treeSet); if i want execute this program i got an Runtime Exception like : Exception in thread "main" java.lang.NullPointerException at java.util.TreeMap.compare(Unknown Source) at java.util.TreeMap.put(Unknown Source) at java.util.TreeSet.add(Unknown Source) at com.practice.collections.TreeSetExample.main(TreeSetExample.java:10) but in your sample example you didn't get any exception ... i got confused which one is correct Sir, You said TreeSet accepted null (for only one time) but in program i got error like what am mention above .... please clarify my doubt ...

[@joerokcz]

if i tried to put null after an null insertion,what will happen?

[@vishwanathtontanal2365]

Null value is not allowed in TreeSet. Not even single time.

[@ajinzrathod]

Allowed till 1.6. Since 1.7, null value is not allowed even for first time.

[@nitishkadam9323]

getting null pointer exception while adding null in empty treeset ?? please explain.. thnks

[@NikhilMaguluri]

from java 7 null insertion is not allowed in a treeset. In java 6 it is a bug, that allows null insertion into a empty treeset.

[@RoyaLockz]

Allowing Null within a collection of unique values is generally considered bad practice and disallowed in a lot of implementations with a similar mentality. Could you describe a situation where you'd need to insert Null into a Set that it'd be beneficial and improve the overall code quality?

[@vineetchaurasia7460]

Null is not allowed

[@srikanthr5935]

Hello sir, i am trying to insert null in an empty treeset but still i am getting null pointer exception does treeset really allows null acceptance for once

[@ishansoni9819]

post ur code?

[@srikanthr5935]

Ishan Soni package name; import java.util.Comparator; import java.util.HashSet; import java.util.TreeSet; public class treeset { public static void main(String []args) { TreeSet t1=new TreeSet(); t1.add(null); System.out.println(t1); } }

[@bluesteel1]

3:21 null insertions are not allowed this is incorrect

[@DurgaSoftwareSolutions]

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[@JorgeChavez8]

Number 6 is wrong, TreeSet doesn't allow you to insert null objects.

[@tx30289]

nice English :)

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[@horriblecoder7280]

his comment was sarcastic.

[@vipulgujarathi_7379]

what is the default size of TreeSet Constructor?

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[@Mbc43m276]

Why are there two separate constructors for creating an equivalent collection c and a sortedSet s? I.e TreeSet t =new TreeSet(Collection c) and TreeSet t =new TreeSet(SortedSet s). ? sorted set comes under the collection interface right? Someone please help

[@horriblecoder7280]

In first type of constructor the element order will be naturally sorted. In second type the element order will depend on the customized sorting order that already may have been used. suppose: contents of List x: 5,3,9,7 TreeSet t=new TreeSet(x); contents of TreeSet t:3,5,7,9 suppose: contents of TreeSet x:5,3,9,7 (custmizing in order is done under compare method) TreeSet t=new TreeSet(x); contents of TreeSet t:5,3,9,7 Hence order also moves. For more info read documentation docs.oracle.com/javase/8/docs/api/java/util/TreeSet.html

[@HemantShori]

you had me at medile

[@shilpa3645]

treeset not allowed null

[@DurgaSoftwareSolutions]

Yah Shilpa until 1.6 version we can add null to the TreeSet. But from 1.7 version onwards we cannot add null to the TreeSet.This is a small difference wrt versions.

[@Nitinkandwal]

null is not allowed in TreeSet.

[@pratikbhardwaj3804]

from 1.7 version

[@surendramishra4813]

Nitin Kandwal first see full video

[@farhadbaghirov9075]

+ Kabir Kandwal null is allowed Let's look at the example shown below: class data1 { Integer number; public data1(Integer number) { this.number = number; } @Override public String toString() { return ""+number; } } TreeSet data2set = new TreeSet(new Comparator() { @Override public int compare(data1 d1,data1 d2) { int d1n=d1==null ? 0 : d1.number; int d2n=d2==null ? 0 : d2.number; return d1n-d2n; } }); data2set.add(null); data2set.addAll(Arrays.asList(null,null)); System.out.println(data2set);//[null]

[@Vishwasp13]

@@farhadbaghirov9075 Customising the comparator and removing null doesn't imply null is allowed. The trick is good but might confuse others.